This invention relates generally to a microfiber substrate of improved carding ability and its manufacturing method, and more particularly to a micro-fiber spun by conjugated melting of crystallization difference of high crystallization polymer and low crystallization polyester, drawn to form an unsplit microfiber staple having a layer of thin film in its surrounding, the said microfiber staple which is still kept in unsplitting state during opening, carding and lapping treatment, will be split just at the layer of thin layer of its surrounding of the said microfiber staple by spunlace to completely split from the said microfiber, knitted to form water-jet punch web, then subject to hot water to shrink to densification.
It is well known that a manufacturing method of suede tone or nubuck tone microfiber web as described in the Japan Laid-Open Patent Application No. 1972-030930 is typical of many of the patents of the prior art, which discloses filaments through conjugate melt by adopting polyester and polyamide in the adjacent spinnerettes are adhered with nonaqueous spinning finishing agent and then aqueous spinning finishing agent, and then the web formed after splitting is subjected to boiling water to split into each component. By using this method, the conjugate filaments will likely to split into each component during drawing and fracture of monofilament will be occurred, this is not suitable for finishing.
Japan Laid-Open Patent Application No. 1976-070366 discloses a manufacturing method of suede tone or nubuck tone microfiber web involving to filaments through conjugate melt by adopting polyester containing 0.05xcx9c1.0 mole % sulfonated metal salt and polyamide in the adjacent spinnerettes and along the tangential direction to the filaments in alternatively located way to obtain hollow ring shape conjugated filaments. After these hollow ring shape conjugated filaments are crimped in the web, dips into warm water that make the shrinkage rate of the conjugated fiber below 10%, bends the web to split into monofilament of each component, and to get a suede tone or nubuck tone microfiber web. By using this method, the conjugate filament will likely to split into each component during drawing and fracture of monofilament will be occurred, this is not suitable for finishing.
From environmental protection standpoint, conventional microfiber is usually manufactured by splitting the filaments, which is spun by adopting splitting type spinnerette, and directly using mechanical means such as spunlace, abrasion, flexing etc., (refer to Japan Laid-Open Patent Application No. 1981-154546, applicant: Kanebo Corporation, Japan), or by using heat treatment means such as hot water, hot air etc., (refer to Japan Laid-Open Patent Application No. 1976-70366, applicant: Teijin Corporation, Japan) to obtain microfiber.
The two component conjugated filament shown in FIG. 2a (FIG. 1 of Japan Laid-Open Patent Application No. 1981-154546) and FIG. 2b (FIG. 2 of Japan Laid-Open Patent Application No. 1976-70366), which is extruded by extruding different component polymers through different spinnerette. The two different component polymers are merely separated by mechanical means or heat treatment to split into microfiber. But this is not suitable due to high cost and high precision equipment involved to this process.
It is apparent that the split section of monofilament as shown in FIGS. 2a and 2b are completely hollow in the surrounding of the two component conjugated filament. The inclined line portion of the monofilament is supposed as A component, while the bold line in FIG. 2a and the blank portion in FIG. 2b is supposed as B component. When the difference of crystallization degree between these two components A and B is too large, the filament obtained apt to split during drawing, opening and carding, it is not suitable for processing and after finishing. To avoid the early splitting, polymer of these two components A and B having approximate crystallization degree is adopted, but bad splitting often occurred in the splitting process and microfiber is not obtained.
Low crystallization degree polymer may be used to obtain filament with shrinkage, but this will cause the filament split too early. How to get a two component conjugated filament with easily split and shrinkable effect is a long-felt subject matter to the person skilled in the art.
In viewing of the above faults, the inventors have studied many polymers of different crystallization degree suitable for spinning into conjugated filament, and discover that polymer of high crystallization degree and polyester of low crystallization degree can be used to spin by conjugated spinning, drawn to form an unsplit microfiber staple having a layer of thin film in its surrounding, the said microfiber staple which is still kept in unsplitting state during opening, carding and lapping treatment, will be split just at the layer of thin layer of its surrounding of the said microfiber staple by spunlace to completely split from the said microfiber, knitted to form water-jet punch web, then subject to hot water to shrink to densification to obtain microfiber substrate. The microfiber substrate of this invention can be obtained by using spunlace, then treated by hot water or hot air shrinking treatment without using solvent, alkali solution. Mechanically physical means and mechanically impingement means and heat treatment used in the splitting of the said microfiber substrate meets the requirement of environmental protection regulation.
It is the object of this invention to provide a microfiber substrate of improved carding ability and its manufacturing method, and more particularly to a microfiber spun by conjugated melting of crystallization difference of high crystallization degree polymer and low crystallization degree polyester, drawn to form an unsplit micro-fiber staple having a layer of thin film in its surrounding, the said micro-fiber staple which is still kept in unsplitting state during opening, carding and lapping treatment, will be split just at the layer of thin layer of its surrounding of the said microfiber staple by spunlace to completely split to get the said microfiber, excellent in carding ability, softness, hand, knitted to form spunlace web, then subject to hot water to shrink to densification.
The spunlace splittable microfiber substrate of this invention which attains the above-mentioned purpose, which is characterized by extruding polymer chip containing high crystallization degree polymer (A) and low crystallization degree polyester (B) in the weight ratio of 5/195xcx9c95/5 used for conjugated melting to spin into filament, when the cross section of the orientation of the diameter of the filament is taken, by using the layout of spinnerette to spin the filament which having high crystallization degree polymer (A) surrounded by low crystallization degree polyester(B). (1) The aforementioned high crystallization degree polymer (A) region is distributed so that the main segment of the configuration which has two or more branching sections which were formed in the fiber center section, and which collected and were extended from the section to the radial toward the fiber front face may be formed. (2) The aforementioned low crystallization degree polyester (B)is distributed in the thin film shape so that it can surround the aforementioned high crystallization degree polymer (A) which extended from the section to the radial toward the fiber front face. (3)The ratio of the thickness of the thin film to the diameter Y of microfiber which have not spunlaced and split is taken as Z in percentage, indicated in term of the diameter Y of microfiber which have not spunlaced and split and the diameter X of microfiber which have spunlaced and split as the relation: Z=(1xe2x88x92X/Y)/2xc3x97100%, 0.1%xe2x89xa6Zxe2x89xa65.0%. The microfiber so obtained is not spunlaced and split (the cross-section of the said unspunlaced and unsplit microfiber is shown as FIG. 1A), then is subject to draw, cut to form an unsplit microfiber staple having a layer of thin film in its surrounding, succeeded by opening, carding and lapping treatment, is knitted to form spunlace web (the cross-section of the spunlaced and split microfiber is shown as FIG. 1B), then is treated by hot water, hot air to shrink to densification.
The spun microfiber obtained before spunlace (water-jet punching) treatment is subject to drawing to get microfiber staple of fineness 1.0xcx9c6.0 denier, then lapping, water-jet punching to split into 4-108 segments to get fineness 0.001xcx9c0.8 denier.